Question

A 0.145 kg baseball is moving at 35 m/s it is caught by a player. What is the change in momentum of the ball?

Answer 1

`-5.075 kg` `m//s`

Explanation:

momentum = mass * velocity

where mass is in kilograms `kg`
and velocity is in metres per second `m//s`.

here, the initial momentum is `0.145kg * 35 m//s`,

which is `5.075kg` `m//s`.

the ball has a momentum of `5.075 kg` `m//s` when it is moving, at a velocity of `35 m//s`.

however, when it is caught by the player, it will not be moving. its velocity will be `0 m//s`.

multiplying `0.145kg` (or indeed any other mass) by `0 m//s` will give `0 kg` `m//s`.
this means that when the ball is not moving, its momentum is zero.

the change in momentum from `5.075kg` `m//s` to `0kg` `m//s` is `-5.075kg` `m//s`.